Sterilization for explosive echo ranging signals



Nov; 12, 1963 c. FISHER ETAL 3,110,877

STERILIZATION FOR EXPLOSIVE ECHO RANGING SIGNALS Filed 001',- 25, 1960 2 Sheets-Sheet l INVENTORS. L. C. FISHER 8 E. H. BEACH Nov. 12, 1963 c. FISHER ETAL 3,110,877

STERILIZATION FOR EXPLOSIVE ECHO RANGING SIGNALS Filed Oct. 25, 1960 2 Sheets-Sheet 2 ELECTRONIC 44 SYSTEM FIRING SWITCH INVENTORS. L. C. FISHER 8 E. H. BEACH )2; ATTYS.

United States Patent Ofiice 3 t 10,877 Patented Nov. 12, 1963 3,110,877 STERILIZATHON FGR EXPLGSHVE ECHU RANGENG SIGNALS Lyman C. Fisher, 12% Schindler Drive, and Eugene l Beach, 12291 Remington Road, both of Silver Spring, Md.

Filed Oct. 25, 1960, Ser. No. 64,970 9 Claims. (Cl. Filth-=) (Granted under Title 35, U3. Code (1952), see. 256) The invention described herein may be manufact red and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to a method and apparatus for use during training exercises with explosive echo ranging charges.

Explosive echo ranging charges are used in modern day warfare to enable airborne personnel to detect the presence of enemy submarines which are beneath the surface of the water. These charges which contain about five pounds of explosive TNT are dropped into the water from an aircraft and explode at a predetermined depth emitting compressional waves which are transmitted through the water. These compressional or sound waves are propagated through the water to a submarine and bounce back to detecting means located on the surface of the water. The detecting apparatus emits radio signals that are received by the aircraft which dropped the charge and the detecting apparatus into the water thus giving an indication of the submarine location.

During training exercises with explosive echo ranging charges, friendly submarines are employed as the simulated enemy target. When the explosive echo ranging charges are dropped into the water and explode in the vicinity of the friendly submarine used during training exercises there is a great probability that damage will be done to the submarine. This damage could be highly costly and possibly even fatal to the members of the submarine crew. Thus, there exists a need for preventing explosion of the echo ranging charge when it is in proximity to a friendly submarine during training exercises.

Accordingly, it is an object of this invention to provide a new and improved apparatus and method for sterilizing explosive echo ran ing charges.

Another object is to provide a new and improved apparatus and method for sterilizing explosive echo ranging charges whereby no damage will be sustained by a friendly submarine during training exercises.

A further object is to provide an explosive echo ranging system and method that may be used during training exercises which is highly reliable, easily reused, selfpowered, inexpensive, and easily installed.

Various other objects and advantages will appear from the following description of one embodiment of the invention and the novel features will be particularly pointed out hereinafter in connection with the appended claims.

The manner which this invention achieves these objects can best be understood by reference to the accompanying drawings in which:

FIG. 1 is an elevational view of the submarine and the associated pressure patterns emitted by the various transducers;

FIG. 2 is a front view of the submarine of FIG. 1 and the Various pressure wave patterns of the associated transducers;

FIG. 3 is an illustration of the modified explosive echo ranging charge partly in section; and

FIG. 4 is a schematic diagram of an electronic system utilized with the explosive echo ranging charge of FIG. 3.

It is to be understood that like reference numerals throughout the various figures will be used to designate like or corresponding parts.

Referring now to the elevational view of the submarine 11 shown on FIG. 1, wherein a plurality of ultrasonic pressure transducers 12, 13 and 14 which are capable of emitting high frequency compressional waves into the surrounding water medium of the submarine are disclosed. The barium titanate crystal transducers 12 and 13 are located on the forward and aft ends respectively of the submarine while the transducer 14 is mounted on the conning tower. These transducers are connected to a suitable electrical or electronic generator 15 that will supply them with signals having frequencies of at least 250 kilocycles per second.

Each of the transducers produces a substantially hemispherical lobe pattern shown at 1o, 17 and is on FIGS. 1 and 2 of the drawings. The radius of each lobe is approximately feet so that the water medium above and to the sides of the submarine will be insonified with ultrasonic waves to a surface where the explosive source Zll, which has been dropped from an aircraft containing personnel being trained in the use of explosive echo ranging charges, might be able to damage the submarine. Thus, the submarine lit will be rendered invulnerable to possible damage from the explosive echo ranging charge when it normally would exploded in the vicinity of the submarine. However, since pressure waves in excess of 250 kilocycles per second are quickly attenuated by a water medium, the explosive sound source will not be operative at any distance much greater than 100 feet from the submarine, thereby rendering it a useful training device.

The generator 15 may be either of the continuous wave type or of the type that emits the 250 kc. signal for a short period of time once in any predetermined period of time. The pulse type operation has the advantage of permitting the charge 21 to be able to discriminate between the actual signal and spurious noise that might be generated in the water.

When the explosive echo ranging charge 21 comes into the vicinity of the submarine and detects the ultrasonic waves produced thereby, the explosive train therein is broken and it is rendered inoperative or sterile. Under normal operating conditions a pressure responsive transducer, diaphragm 22, located in an opening of the exterior shell of the explosive echo ranging charge 21, as shown on the partial section view of FIG. 3, is actuated when the explosive sound source reaches a predetermined depth in the water. When the diaphragm is actuated, assembly 23 is translated upwardly (as shown on the drawings) compressing spring 25 and lining up primer 24 carried therein with detonator 26 and electrical contact 43 connected to lead 44.

Another pressure responsive detector, diaphragm 28, is located near the forward end of the explosive echo ranging charge and will be actuated when the depth of the charge reaches a predetermined value which is in excess of the value which will actuate diaphragm 22. Hydrostatic diaphragm 28 energizes firing switch 29 which in turn permits electrical actuation of primer Z4 and detonator 26 thereby causing actuation of booster element 32, located in the midportion of the charged body. Surrounding booster 32 is a high explosive charge 33, for example, TllT, which will explode in response to the signal supplied from booster 32. thereto.

The explosive charge generates audio frequency com pressional or acoustic waves through the water medium in which it has been dropped that may be reflected from a suitable target, such as a submarine, and detected by a suitable electroacoustic transducer located on the surface of the water. in order to detect the signals emanating from the submarine transducers l2, l3 and 14, the explosive echo ranging charge contains an ultrasonic transducer 34 located in the nose portion thereof and preferably made of the same material as transducers l2, l3 and 14. When one or more of the ultrasonic pressure waves forming lobes 16, 1'7 or 13 is detected by transducer 34- prior to the actuation of firing switch 29, the primer firing circuit is broken. The fin assembly 35 located at the aft end of the explosive sound source 21 provides stabilization therefore while it is falling through the air and dropping through the water, thus the downward position of transducer 34 is maintained.

Referring now to FIG. 4 of the drawings, which is a schematic diagram of a preferred electronic system utilized in the explosive sound source 21. The output of transducer 34 is fed to a receiver containing bandpass filter 37 and amplifier 36 which may take any suitable form but is preferably of the transistorized type. The amplified output signal produced by amplifier 36 is fed to bandpass filter 37 having a center frequency substantially equal to the frequency of the signals generated by transmitter aboard submarine 11. The filter 37 must be capable of passing a fairly wide band of frequencies because of the Doppler effect which will occur as the charge moves relative to the submarine. The output of bandpass filter 37 is coupled to normally open switch 33, which is preferably a transistor switch normally biased beyond cutoff. The other input terminal to switch 38 is connected to one side of a frangible element which preferably takes the form of electric fuse 39, the other side of the fuse being connected to one terminal of battery 41. Fuse 39 is also connected to one terminal of the hydrostatic firing switch 29, the other terminal of switch 29 being connected to lead 44 which is connected to contact 43 thereby forming a firing circuit for primer 24-, the other end of which is grounded as at 30.

Under normal operating conditions, i.e., when no signal is received by transducer 34 and hydrostatic transducers 22 and 28 are actuated, primer 24 is lined up with contact 43 and firing switch 29 is thereafter closed thereby causing current to flow from battery 41 through the fuse 39, firing switch 29, lead 4-4, contact 43 and heating element 27 which is connected to the other terminal of battery 41 by way of ground connection 31 and contained Within primer 24. When current flows through heating element 27, its temperature is increased thereby transmitting heat to primer 24 in which it is imbedded. When sufiicient heat energy is imparted to the primer by element 27, it is ignited. Ignition of primer 24 causes actuation of detonator 26 which explodes. The explosion of detonator 26 is passed on to booster 32 and thence to high explosive charge 33 in a conventional manner.

When a signal is received by transducer 34- it causes switch 38 to be closed thereby providing a short circuit from battery 41 through fuse 39 and switch 33 to the ground terminal. The resulting high amplitude current through fuse 39 causes it to be severed thereby rendering the explosive firing circuit ineffective. If pulse operation is employed, switch 38 may contain a capacitor which will be progressively charged in response to each of the pulses detected by transducer 34. When a sufiicient number of pulses have been received so as to close the switch in response to the accumulated charge across the capacitor, the fuse will be shortcircuited thereby permitting discrimination between possible spurious noise sources and an actual signal.

It should now be apparent that there has been herein disclosed a system and method for rendering explosive echo ranging charges safe for use during training exercises so that no damage may be inflicted upon a submarine with which the charges are being used in training.

It will be understood that various changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principles and scope of the invention as expressed in the appended claims. For instance, the explosive sound source can contain an arming device responsive to the initial dropping of the sound source from the aircraft and may also contain an impact actuating switch as well as the hydrostatic actuating switches described in detail herein.

What is claimed is:

1. Apparatus for sterilizing an explosive sound source with ultrasonic compressional waves ha ing a frequency of at least 250 kilocycles generated by a submerged submarine comprising means contained within the sound source for detecting the ultrasonic waves, a firing circuit coupled to said detecting means, said firing circuit including means for rendering it ineffective in response to a signal generated by said detecting means when the ultrasonic waves are received thereby, an explosive firing train contained within the sound source, and transducer means coupled to said firing train for lining the firing train up with a portion of the firing circuit in response to a predetermined external condition.

2. The apparatus of claim 1 wherein the detecting means comprises an electroacoustic transducer.

3. The apparatus of claim 1 wherein said transmitting transducer means includes a plurality of transducers mounted at different points on the submarine.

4. The apparatus of claim 2 wherein one of said transducer means is mounted on each end of the submarine deck and another transducer means is mounted on the submarine conning tower.

5. Apparatus for sterilizing an explosive sound source with ultrasonic compressional waves of predetermined frequency of at least 250 kilocycles generated by a submerged submarine comprising means contained within the sound source for detecting the ultrasonic waves, a firing circuit coupled to said detecting means, said firing circuit including means for rendering it ineffective in response to a signal generated by said detecting means when ultrasonic waves of the predetermined frequency are received thereby, an explosive firing train contained within the sound source, a first hydrostatic detector coupled to said firing train for lining the firing train up with a portion of the firing circuit in response to a first predetermined pressure exerted thereon, and a second hydrostatic detector coupled to said firing circuit for completing a circuit between the firing circuit and the firing train in response to a second predetermined pressure in excess of the first predetermined pressure is exerted thereon.

6. The apparatus of claim 5 wherein said detecting means comprises an electroacoustic transducer.

7. The apparatus of claim 6 wherein said detecting means comprises a bandpass filter having a center fre quency substantially the same as the predetermined frequency.

8. The apparatus of claim 5 wherein said means for rendering the firing circuit ineffective comprises an electrical fuse and a normally open switch coupled to said fuse, said switch being closed when the ultrasonic waves are received by said detecting means.

9. A method for sterilizing an explosive echo sound source that normally Will be rendered operative upon reaching a first predetermined Water depth, comprising the steps of dropping the sound source into a water medium in which a submarine is located, lining up the explosive train of the sound source when it reaches a second predetermined depth less than the first depth, producing ultrasonic compressional \Waves having a frequency of at least 250 kilocycles in the water medium above and to the sides of the submarine to a surface Where the explosive source can damage the submarine, detecting the ultrasonic waves, and rendering the sound source ineffective in response to the detected signal.

References Cited in the file of this patent UNlTED STATES PATENTS 1,407,653 Hammond Feb. 21, 1922 2,505,000 Moore Apr. 25, 1950 2,703,873 Rockwell Mar. 8, 1955 2,961,954 Moore et a1 Nov. 29, 1960 2,961,956 Townsend Nov. 29, 1960 OTHER REFERENCES Fishing Sonar Uses Compact Scan System, by Nishiinure et 211., Electronics, vol. 32, No. 14, April 3, 1059 (pp. 54-56 relied on). 

1. APPARATUS FOR STERILIZING AN EXPLOSIVE SOUND SOURCE WITH ULTRASONIC COMPRESSIONAL WAVES HAVING A FREQUENCY OF AT LEAST 250 KILOCYCLES GENERATED BY A SUBMERGED SUBMARINE COMPRISING MEANS CONTAINED WITHIN THE SOUND SOURCE FOR DETECTING THE ULTRASONIC WAVES, A FIRING CIRCUIT COUPLED TO SAID DETECTING MEANS, SAID FIRING CIRCUIT INCLUDING MEANS FOR RENDERING IT INEFFECTIVE IN RESPONSE TO A SIGNAL GENERATED BY SAID DETECTING MEANS WHEN THE ULTRASONIC WAVES ARE RECEIVED THEREBY, AN EXPLOSIVE FIRING TRAIN CONTAINED WITHIN THE SOUND SOURCE, AND TRANSDUCER MEANS COUPLED TO SAID FIRING TRAIN FOR LINING THE FIRING TRAIN UP 